From patchwork Thu Oct 8 14:08:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11823017 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1AECC4363A for ; Thu, 8 Oct 2020 14:09:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 907C12184D for ; Thu, 8 Oct 2020 14:09:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="au2nTZHO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730461AbgJHOJL (ORCPT ); Thu, 8 Oct 2020 10:09:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:47863 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730175AbgJHOJJ (ORCPT ); Thu, 8 Oct 2020 10:09:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602166147; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=lNg244olvJnrEe+Em6GeVtepoBO4gPo9xXAtNaqbKRU=; b=au2nTZHOPas3y06QbtzLPpIbCDwjGZxd6Gl5iRygFA3qecj9ZYExs4+LAkajg2cEb5jasJ 8iFuFpWB3YadUXQnYbCeBGxOy5boHjnuPvswdabDHgk5YYvA1ZPN1+I0M4qRNe5xN0550u fLu9h12eSYIRFwrt42Xo2AiFqzM5Wfg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-123-_cGUMrveO1-TQBzDaZONvQ-1; Thu, 08 Oct 2020 10:09:03 -0400 X-MC-Unique: _cGUMrveO1-TQBzDaZONvQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8053E1074644; Thu, 8 Oct 2020 14:09:01 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 82A01757DF; Thu, 8 Oct 2020 14:08:58 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 5DB5330736C8B; Thu, 8 Oct 2020 16:08:57 +0200 (CEST) Subject: [PATCH bpf-next V3 0/6] bpf: New approach for BPF MTU handling From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com Date: Thu, 08 Oct 2020 16:08:57 +0200 Message-ID: <160216609656.882446.16642490462568561112.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org This patchset drops all the MTU checks in TC BPF-helpers that limits growing the packet size. This is done because these BPF-helpers doesn't take redirect into account, which can result in their MTU check being done against the wrong netdev. The new approach is to give BPF-programs knowledge about the MTU on a netdev (via ifindex) and fib route lookup level. Meaning some BPF-helpers are added and extended to make it possible to do MTU checks in the BPF-code. If BPF-prog doesn't comply with the MTU then the packet will eventually get dropped as some other layer. In some cases the existing kernel MTU checks will drop the packet, but there are also cases where BPF can bypass these checks. Specifically doing TC-redirect from ingress step (sch_handle_ingress) into egress code path (basically calling dev_queue_xmit()). It is left up to driver code to handle these kind of MTU violations. One advantage of this approach is that it ingress-to-egress BPF-prog can send information via packet data. With the MTU checks removed in the helpers, and also not done in skb_do_redirect() call, this allows for an ingress BPF-prog to communicate with an egress BPF-prog via packet data, as long as egress BPF-prog remove this prior to transmitting packet. This patchset is primarily focused on TC-BPF, but I've made sure that the MTU BPF-helpers also works for XDP BPF-programs. V2: Change BPF-helper API from lookup to check V3: Drop enforcement of MTU in net-core, leave it to drivers --- Jesper Dangaard Brouer (6): bpf: Remove MTU check in __bpf_skb_max_len bpf: bpf_fib_lookup return MTU value as output when looked up bpf: add BPF-helper for MTU checking bpf: make it possible to identify BPF redirected SKBs bpf: drop MTU check when doing TC-BPF redirect to ingress net: inline and splitup is_skb_forwardable include/linux/netdevice.h | 32 +++++++- include/uapi/linux/bpf.h | 74 +++++++++++++++++- net/core/dev.c | 25 +----- net/core/filter.c | 166 ++++++++++++++++++++++++++++++++++++---- net/sched/Kconfig | 1 tools/include/uapi/linux/bpf.h | 74 +++++++++++++++++- 6 files changed, 326 insertions(+), 46 deletions(-) -- Signature